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k6 vs Locust: open-source performance and load testing tools compared

Metrics as of , from the GitHub or GitLab API of each repository. Refreshed monthly.

Summary

k6: Load-testing tool that runs JavaScript test scripts from the CLI, in CI or on Kubernetes.

Locust: Load testing tool for HTTP and other protocols with scenarios written in Python and a web UI.

Both are listed under Performance and load testing. The table gives repository metrics from the GitHub API with their fetch date, then the documented facts used for every comparison in this category, each linked to the README or docs page it comes from. A cell reads "not documented" when the fact was not found in the project's documentation; that does not mean the feature is absent.

Side by side

k6 and Locust: metrics and documented facts, in the fixed row order used for performance and load testing comparisons.
Factk6Locust
Stars31,548128,1771
Forks1,63513,2461
Contributors28914041
Last release2026-09-2112026-09-171
Last commit2026-09-2212026-09-211
Commits in 90 days17711601
LicenseAGPL-3.01MIT1
Primary languageGo1Python1
Statusactive1active1
ProtocolsHTTP, WebSockets, gRPC, browser; more through extensions source: READMEHTTP; other protocols and systems through user-written clients source: README
Test authoring formatCode (JavaScript test scripts run by an embedded engine) source: READMECode (Python locustfiles) source: README
Distributed or parallel loadDistributed tests on Kubernetes with the k6-operator (TestRun parallelism) source: Docs: Running distributed testsDistributed runs with one --master process and one or more --worker processes, on one or several machines source: Docs: Distributed load generation
CI integrationIntegration guides for GitHub Actions, GitLab, Jenkins, CircleCI, Azure Pipelines, TeamCity and others source: Docs: Integrations and toolsHeadless mode in CI/CD pipelines, with a GitHub Actions example source: Docs: Running without the web UI
Report formatsEnd-of-test summary; CSV and JSON files; streaming to InfluxDB, Prometheus remote write, Datadog, OpenTelemetry and others source: Docs: Real timeCSV stats files (--csv), HTML report (--html), JSON stats (--json) source: Docs: Configuration
Install methodPackages for Linux, macOS and Windows (apt, dnf, brew, winget); Docker image grafana/k6; standalone binary source: Docs: Install k6pip (pip install locust) source: Docs: Installation

1 Fetched from the GitHub or GitLab API on . Hover a value for its own date.

When each fits

Written from each project's documented scope, not from preference. Neither tool is ranked.

k6

Fits projects that load test services with test scripts kept as code; its README describes scripts that run on the CLI, in CI or across a Kubernetes cluster. source: README

Locust

Fits projects that load test HTTP services and other protocols; its README describes tests defined in regular Python code. source: README

More on these tools

Sources

  1. GitHub REST API: repository, read
  2. GitHub REST API: repository, read
  3. GitHub REST API: contributors, read
  4. GitHub REST API: contributors, read
  5. GitHub REST API: latest release, read
  6. GitHub REST API: latest release, read
  7. GitHub REST API: commits, read
  8. GitHub REST API: commits, read
  9. README, read
  10. README, read
  11. Docs: Running distributed tests, read
  12. Docs: Distributed load generation, read
  13. Docs: Integrations and tools, read
  14. Docs: Running without the web UI, read
  15. Docs: Real time, read
  16. Docs: Configuration, read
  17. Docs: Install k6, read
  18. Docs: Installation, read

Documented facts collected 2026-09-22. See the methodology for how metrics and facts are gathered.